Changes in intraocular pressure during coronary artery bypass graft surgery: an observational study.

BACKGROUND: In this study, the effects of pulsatile and non-pulsatile on-pump Coronary Artery Bypass Graft surgery (CABG) and off-pump CABG techniques on the intraocular pressure were investigated.

METHODS: Forty-five patients who planned to elective coronary artery bypass surgery with on-pump pulsatile (n=15), non-pulsatile (n=15), or off-pump (n=15) were included. Intraocular Pressure (IOP) measurements were performed on both eyes at nine time-points: 1) Before the operation, 2) After anesthesia induction, 3) 3 minutes after heparin administration Left Internal Mammary Artery (LIMA) harvesting, 4) End of the first anastomosis, 5) End of LIMA anastomosis, 6) 3 minutes after protamine administration, 7) End of the operation, and 8) Second hour in Intensive Care Unit (ICU), 9) Fifth hour in ICU. Mean Arterial Pressure (MAP) and Central Venous Pressure (CVP) were also recorded at the same time points as IOP.

RESULTS: In Cardiopulmonary Bypass (CPB) groups (pulsatile or non-pulsatile CPB) with the beginning of CPB, there were significant decreases in IOP values when compared to baseline (p=0.012). This decrease was more prominent in the non-pulsatile group when compared to the pulsatile group (T4 IOP values: pulsatile, 9.7±2.6; non-pulsatile, 6.8±1.9; p=0.002; T5 IOP values: pulsatile, 9.5±1.9; non-pulsatile, 6.7±2.1; p=0.004). At the end of the surgery (T7 ), IOP values returned to the baseline and stayed stable at the remaining time-points. In-off pump group, IOP values significantly increased with a head-down position (T4 IOP values: off-pump surgery, 19.7±5.2; p=0.015). IOP values remained high until the normalization of head-down position (T6 ) and stayed stable through the rest of all remaining time-points.

CONCLUSION: During cardiac surgery regardless of the technique (on-pump CABG, off-pump CABG), intraocular pressures remain in the normal ranges. It should be kept in mind that patients should be avoided from long and extreme Trendelenburg position, low CVP, and MAP levels during cardiac surgery to prevent eye-related complications.